Linux User & Developer的No. 169目录

This issue » Electronics for Pi hackers » Ultimate rescue kit » Revitalise an old laptop » Manage the Ubuntu system Welcome to the latest issue of Linux User & Developer, the UK and America’s favourite Linux and open source magazine. The Raspberry Pi has been a runaway success story since its launch in 2012, and it’s at the heart of many fantastic maker projects. We often talk about the Pi being a great device for getting people coding, but what about if you’re an experienced coder who’d like to create the kind of advanced hardware projects that have inspired so many of us? That’s where our feature on p58 this issue comes in. It explains all the electronics a budding Pi hacker needs to know, from detailing all of…

Established back in 1995 in a bid to defend Linux against intellectual property attacks, the Open Invention Network was spearheaded by an array of leading technology brands. While the likes of Red Hat, Sony, IBM and Philips are all credited with launching the alliance, it has grown dramatically to cover many areas outside of core technology companies. One of the last remaining areas not to get heavily involved with the Open Invention Network has been the automotive industry, but that has just changed for the better. Toyota has led a wave of leading automotive manufacturers to join the network and their reasons for doing so are clear. With the rise of self-driving cars, many of which are embracing the open-source ethos, patent protection is at an all-time high. Also joining…

Top 10 This month • Stable releases (15) In development (6) The CentOS 6.8 release has been received well by users. It features a number of fresh changes, including a combined repository for installation. Highlights elementary OS The second beta of the elementary OS 0.4 update has garnered plenty of love this past month. Over 70 issues have been fixed and patched since its previous update, making it one of the more complete beta packages out there. Linux Mint Mint is still riding the crest of the wave from its amazing Mint 18 update. We reviewed it this issue, and found it to be one of the best releases based on Ubuntu 16.04. Manjaro While Zorin still provides one of the better ways for users to get started with Linux,…

Bluetooth LE Expansion This USB expansion adds Bluetooth 4.1 connectivity to the Omega2, so that it can interact with a range of Bluetooth-connected devices. It’s also compatible with most smartphones running iOS 5+ and Android 4.3+. Mini Dock The Mini Dock is designed to help power your Omega for apps that do not require or use its GPIO pins. Its small size means it’s a handy accessory to have when it comes to using it alongside wireless applications such as video streaming and printing. Ethernet Expansion As its name suggests, this expansions adds a 100mbps Ethernet port to the Omega2. The unit plugs direction to the Expansion Dock, which you’ll also need to buy. The Ethernet Expansion is particularly handy when it comes to quickly reflashing the firmware of an…

Recover photos and data Lost data is one of the most common problems for computer users across all platforms, but in most cases the data will persist on your hard disk drive even though it is invisible to the operating system. A successful data recovery tool should handle photos, videos and other user-generated data. Recover lost partitions Lost HDD partitions can be recovered with disk-specific recovery tools, typically allowing you to make partition-level fixes. Additionally, such tools should let you recover partitions, make disks bootable, restore boot sectors, and undelete and copy files from NTFS, FAT, exFAT and ext2 file systems, enabling data recovery from any operating system. Clone your HDD For disks that are about to fail, time is of the essence, and your priority should be to find…

“Fundamentally, it is part of a larger movement toward providing .NET developers a new level of choice, flexibility, and openness in helping to shape the future direction of .NET” Resources GitHub CoreCLR Repository https://github.com/dotnet/coreclr GitHub CoreFx Repository https://github.com/dotnet/corefx GitHub .NET CLI Tools Repository https://github.com/dotnet/cli Debian installation instructions https://www.microsoft.com/net/core#debian CentOS installation instructions https://www.microsoft.com/net/core#centos Microsoft is delivering on its new love for Linux. A new modularized form of the .NET technology base called .NET Core is now available across several Linux distros. Microsoft has partnered with Canonical and is readying support for Bash on Ubuntu on Windows that includes integrated Linux-based file system support. A new version of SQL Server that runs on Linux is on the horizon. Red Hat has joined the Technical Steering Group of the .NET Foundation, an organisation…

Resources Ansible ansible.com Software systems these days are significantly large, complex and critical. With the cost of development going up, automation of activities like testing, monitoring and building software offers a great deal of cost and simplification benefits. Automation can also help speed up the development of software systems. The goal is to partially or fully automate activities, thereby significantly increasing both quality and productivity. In line with these developments, several tools have been launched to help you automate your software processes. One of the most famous of them is Ansible by Red Hat. Ansible is an open source IT configuration management, deployment and orchestration tool. Designed to be minimal, secure and highly reliable, Ansible has an extremely low learning curve for software development stakeholders. Ansible Tower is an add-on…

Perhaps you can easily churn out code to run on your Raspberry Pi but, sooner or later, you’ll probably have a hankering to interface it to LEDs, sensors and other real-world devices. Sure you can easily attach a ready made board, perhaps a HAT, to the Pi’s GPIO connector, but if you want to go further your C++ or Python programming skills aren’t going to help. The web is awash with circuits for the Pi, ranging from simple ones to light-up LEDs, through PIC programmers to ambitious home automation projects. But to turn these from a circuit diagram into a working circuit requires some electronic skills. Here we’ll teach you how to build an electronic circuit from a circuit diagram. In addition to helping you build circuits that others have…

Most email servers use one of two communication protocols “ Since the Raspberry Pi is such a small computer, it gets used in a lot of projects where you want to monitor a source of data. One such monitor you might want to create is a mail-checker that can display your current unread emails. This issue, we’ll look at how to use Python to create your own mail-checking monitor to run on your Pi. We’ll focus on the communications between the Pi and the mail server and not worry too much about how it might be displayed. That will be left as a further exercise. To start with, most email servers use one of two different communication protocols. The older, simpler one was called POP (Post Office Protocol), and the…

What you’ll need RISC OS Monitor Keyboard Three buttoned mouse (a standard clickable scrollwheel should suffice) You’re happy using Raspbian to get the most from your Raspberry Pi. You might have flirted with the idea of Ubuntu or Arch Linux, but never seen the point. After all, when it comes to maximising what you can do with the Pi, the official distro has everything you need, right? But, what about trying a non-Linux operating system? The Cambridge-developed RISC OS (RISC being an acronym for ‘reduced instruction set computing’) was the first operating system for ARM processors, and although older British readers will recall it from the classic Acorn Archimedes computers, RISC OS remains relevant and easy to get started with. Just make sure you’ve got a monitor, mouse and keyboard…

Thanks to the Slack-driven resurgence in the popularity of in-browser text chat, as well as mobile-friendly “chat to an advisor” options on many websites, you may feel you need to offer a chat client integrated into your own web application – for your own XMPP server or a public one. In which case, Converse.js has to be on your shortlist, for its features and easy integration with popular web platforms from Rails and Django through to Alfresco and WordPress. You can also use it as a standalone client, setting it up on a page of your own, to add Jabber everywhere from your Raspberry Pi to your laptop. With “single and multiuser chats, invitations, service discovery, direct registration, contact lists, roosters and vCard exchange, status changes and messages, typing and…

1 Scientific Linux Scientific Linux is definitely for those who have spent years learning the ins and outs of the wonderful world of Linux distributions. It includes a variety of packages; including Cluster Suite, FUSE and Squashfs, which all work in tandem with one another in order to create a seamless user experience. 2 Yellow Dog Although Yellow Dog was originally released for use on early Apple computers, under its current management, it has been transformed in to a high-performance distribution that doesn’t have a steep learning curve. 3 Ubuntu Studio Whether you’re into music, video or photography, Ubuntu Studio is the ideal choice for media enthusiasts. It comes packed with an array of media-friendly apps and a host of helpful editing tools to boot. 4 Parted Magic Parted Magic…

Over 85 million Android devices have been taken over by a group of China-based cybercriminals, who have created the root-based HummingBad malicious code. The malware looks to establish a rootkit on its target device, which in turn looks to install fraudulent apps and spam ad revenue. If HummingBad is unable to implant the rootkit, it instead mass-spams an array of fraudulent apps. As expected, the device then becomes unusable. No matter what areas of the HummingBad install fail, the blend of several malicious components is so toxic that it actually makes it near-impossible for any infected Android smartphone to not suffer the consequences. According to a report from Check Point, the team that is behind HummingBad has been generating revenue of US$300,000 a month targeting Android smartphones. The number of…

“Where did the idea for Omega2 come from? Was the development process a long one? We really started working on the Omega2 a few months after our last campaign for the Omega1 had finished. The objective for the Omega1 was to bring over the powerful technologies used in web development to the world of hardware development. In other words, the Omega1 was a hardware development board for software developers. That worked very well, and we introduced over 10,000 software developers to hardware development for the first time. But we didn’t want to stop there; instead we wanted to get even more people, ideally everyone, to join the maker movement. So we went out and did some market research. After a lot of research, we found two things in particular. One,…

“Linus Torvalds announced Linux 4.7 (final) roughly when expected (under the revised schedule including a one week slip for his travel plans, which had resulted in an additional week between added between rc7 and final). In his announcement email, Torvalds noted that the patch delta between 4.7-rc7 and final was mostly just trivial one-liner fixes even given the extra week. He added that, “Judging by the linux-next contents” Linux 4.8 was “going to be a bigger release than the current one (4.7 really was fairly calm, I blame at least partly summer in the northern hemisphere)”. Linux 4.7 includes a number of new features, including support for parallel directory lookups for entries within the same filesystem directory (which will really improve performance when dealing with large directories filled with very…

In this feature, we’ve taken a look at a whole host of Linux rescue tools that you’ll find on this issue's cover disc. They will prove incredibly useful for cloning dying disk drives, removing malware and rootkits, and finding lost data. If your problem is a simple forgotten root password, however, you’ll be able to uncover this without additional software or a boot disc (although the latter may prove useful with some distros, for repairing or reinstalling the bootloader, for example). When you reboot your Linux installation (and we’re looking at this from the viewpoint of an Ubuntu 16.04 user) to display the GRUB boot menu, you’ll be presented with a menu and various additional options that you usually ignore. However, with a bit of clever editing, you’ll find that…

In one sense, the ability to develop C# code and run .NET binaries in the Linux environment is not new. Mono has been available in the repositories of most Linux distros for years now. So how does .NET Core compare to Mono? Like Mono, the .NET Core technology base is open-source. Microsoft has placed components of .NET Core under the MIT license, which is a highly permissive Open-Source Software (OSS) license type. And similar to Mono, .NET Core also offers cross platform support and can be run on different types of Linux distros such as Debian, CentOS, OpenSUSE, RedHat and Ubuntu. There are differences however, with the most significant being that .NET Core will continue to be led and officially supported by Microsoft with new feature development and regular releases…

“There is a real requirement to monitor system resources such as memory, CPU and device usage over time” Resources Ubuntu Linux server monitoring and management bit.ly/2agfqcK Linux system administration and configuration bit.ly/1N2N1tt Server management bit.ly/1jKdVmc Without careful management, you can expect that the demands on your Ubuntu Linux system can exceed the resources that are available. There is a real requirement to monitor system resources such as memory, CPU and device usage over time and this will ensure that the system has enough resources to do what you need it to. In a similar way, it is also important to manage the other aspects of your system, such as the various device drivers it uses and how the boot process works. This will help in avoiding performance problems and system…

Resistor values are measured in Ohms (›), k› (103 Ohms) and M› (106 Ohms). Commonly on circuit diagrams, the › is omitted and k, M or R (for ›) replaces the decimal point, e.g. 3R3, 47k and 2M2. Most resistors have a power rating of 0.25W but, if a greater value is specified, do use it. Resistors are marked with coloured bands to represent their value. The last band, separated by a larger gap, represents the tolerance, usually silver (10%) or gold (5%). If there are four bands, the first two represent digits and the third is a multiplier (i.e. number of zeros); with five bands, the first three are digits and the fourth is the multiplier. Black, brown, red, orange, yellow, green, blue, violet, grey and white represent 0-9…

Soldering is an essential skill in electronic construction, and while it’s not difficult, it’s unlikely you’ll have success without some guidance. In particular, unless you know what you’re doing, you could fail to make soldered joints at all, you could solder a larger area than intended thereby making unintended electrical connections, or you could make a dry joint. Here we guide you through the basic steps and we suggest you try this out to get some practice before building a real circuit. 01 Warm up your soldering iron Before you can do anything with your soldering iron it needs to be warmed up to its correct operating temperature so turn it on and wait. Resist the temptation to check whether it’s hot enough with your fingers (it’ll hurt) and you’ll…

When did you start making projects with the Raspberry Pi? I started with an original Pi Model B, by keeping it on a shelf for over a year. One day I saw an Adafruit tutorial about turning an LED on and off in code and had to try it out. After an initial success I started buying every sensor I could find on eBay and trying them out. How experienced with hardware were you before you started using the Pi? I had zero experience of micro-controllers. I had built PCs from parts but that was all. I didn’t even know how to use a breadboard. What electronics skills do you think people need to know to get the most from the Pi? For me it was learning to use a…

In the main body of the article, we have only looked at how to connect to an email server and how to read from it. But what if you need to be able to also send emails off using some code? Similar to poplib and imaplib, the Python standard library includes a module called smtplib. Again, similar to poplib and imaplib, you need to create an SMTP object for the connection, and then log in to the server. If you are using the GMail SMTP server, you could use the code This code asks the end user for their password, but if you aren't concerned about security, you could have it hard-coded into the code. Also, you only need to use the login() method for those servers that require it.…

What you’ll need ArticlesGithub repository ( Explorer Robot as built in Part two Genuine Wiimote (optional) This tutorial builds the software to control your explorer robot so you can let it loose in the living room, the office or even in the garden. We will put together a program to drive the robot from a console, letting you type in WASD as if in a computer game. This gives you a chance to get comfortable with how the robot moves and how the code is put together. We will then go on to integrate a Nintendo Wiimote controller, which makes for a much more natural controller than a keyboard for a more enjoyable experience. The code will be written in Python, which is pre-installed on Raspbian, and wherever…

“ Everything from arranging hot corners to windows tiling has been made available from the start ” RAM 512mb Storage 9GB (20GB recommended) Specs 1024 x 768 resolution 64 and 32-bit versions If you head over to every Linux enthusiast’s friend, DistroWatch, chances are you’ll have seen Linux Mint sitting pretty at the top of its download list for some time now. While it may not be the first distro on everyone’s lips, it’s carved out a solid reputation for being one of the premier routes for Linux newcomers seeking an entry point when changing up their desktop experience. As with most Linux Mint updates we’ve seen previously, changes are plentiful and there’s continued support for both Cinnamon 3 and MATE. No matter your choice, bundled software is minimal…

matplotlib is one of the jewels in Python’s crown. Together with NumPy, it gives users a mathematical teaching tool with some advantages over the proprietary MATLAB, but provides a similar interface for those who’ve used MATLAB in education. Use within IPython and you’ll see one of the best interactive interfaces. Its only disadvantage is it lacks the multi-language accessibility of Gnuplot, but with Python (and Julia, which can access matplotlib via the PyPlot package) in the ascendency in scientific computing, finance, and Big Data, this is not such a handicap. We looked at the third beta release: it’s an easy install, with many Python users and coders likely to have most of the dependencies, but publication lag being what it is, there may be a full release and package for…

“ A state-of-the-art data centre environment enables Netcetera to offer your business enterprise-level colocation and hosted solutions ” Featured host: 0800 808 5450 About us Formed in 1996, Netcetera is one of Europe’s leading web hosting service providers, with customers in over 75 countries worldwide. As the premier provider of datacentre colocation, cloud hosting, dedicated servers and managed web hosting services in the UK, Netcetera offers an array of services designed to more effectively manage IT infrastructures. A state-of-the-art data centre environment enables Netcetera to offer your business enterprise-level colocation and hosted solutions. Providing an unmatched value for your budget is the driving force behind our customer and managed infrastructure services. From single server to fully customised data centre suites, we focus on the IT solutions you need. What we…

“Expect to be able to build things like a USB camera, a GPS system, a USB Wi-Fi device and a multi-media streamer. The only real limit is your own creativity and imagination.” Of course the Raspberry Pi is no expensive piece of kit; in fact, it’s one of the best ways for budding builders and tinkerers to get themselves started with computing without breaking the bank. With units of the original Pi and its numerous successors selling in their millions, it was inevitable that a whole host of competitors would try and get in on the action. We’ve encountered many of them during our time on Linux User & Developer, and it’s truly hard to beat the value for money and ease-of-use that the Raspberry Pi can offer. One of…

An all-new cloud environment for business-to-business networks will allow companies to test the privacy, performance and interoperability of their ecosystems, on a wide spread scale that simply wasn’t available previously. Launched by IBM, Blockchain is currently in beta, but is largely expected to be made available by the end of 2016. Blockchain primarily consists of a distributed database, offering a secure way for companies to store records and other important data. For small businesses, it’s seen as a great way to manage accounts, while for larger businesses, it’s a new way to manage digital assets and stay in control of other keys areas of the business. The new environment is currently undergoing work on a massive scale, aimed at ironing out key security issues before its full launch. It should…

Whether you’ve lost data and need a means to recover it, or you have an HDD infected with a worm, or have a corrupted GRUB boot loader, or some other hardware or operating system issue that cannot be resolved using an installed OS, then what you need is a rescue disc. While you might think that such a collection of tools can be tricky to squeeze onto a single CD or DVD-ROM, the truth is that you can get some very useful data recovery, diagnostic, anti-virus utilities, and more, in some of the smallest Linux distros available. They’re not just for optical media either – you can flash these distros to a USB stick for portable convenience. In fact, the options here are considerable, from individual FOSS utilities and applications…

If you wish to recover data from old, corrupt, scratched, or even decaying CD- or DVD-ROMs (older CDs are prone to chemical oxidization, a process known as disc rot) then the Linux rescue disc app you need to be looking at is Safecopy, a command-line tool that can read damaged optical discs and retrieve lost data. This means that not only can you retrieve individual files, you can also make an image of the entire disc, and then scan the resulting image file to find the data you’re looking for. Reading corrupted discs can be tricky, however, and unless you’re using a suitable device, you’ll have trouble recovering anything. Rather than a standard CD or DVD reader, you’ll need to employ a DVD rewriter, as these are more precise. Alternatively,…

“The Bash shell can be combined with a bunch of useful system commands to create nifty scripts dedicated to file system traversal” Resources Bash gnu.org/software/ bash No matter how well designed a file structure might be, as time goes by, documents will be lost to the sands of time. The Bash shell can be combined with a bunch of useful system commands to create nifty scripts dedicated to file system traversal. In addition to that, the ever-useful grep utility can be used to analyse the contents of files. When done right, a well-designed Bash script even opens the files of interest in an editor of choice, thereby freeing up precious time which can then be used on other tasks. Using shell commands with Bash requires us to warm up an…

Resources Elementary OS https://elementary.io/ unetbootin https://unetbootin.github.io/ EaseUS Todo Backup http://www.todo-backup.com/ Ubuntu http://www.ubuntu.com/ Lubuntu http://lubuntu.net/ Ubuntu Mate https://ubuntu-mate.org/ Puppy Linux http://puppylinux.org/ Debian https://www.debian.org/ VirtualBox https://www.virtualbox.org/ Midori http://midori-browser.org/ Vivaldi https://vivaldi.com/ QupZilla http://www.qupzilla.com/ AdBlock Plus https://adblockplus.org/ LibreOffice https://www.libreoffice.org/ OooLight http://bit.ly/2auhV0p Android-X86 http://bit.ly/1AQYvqj CloudReady http://www.neverware.com/ If you’re a keen observer of PC hardware, you may have noticed that in recent times, the increase in power of desktop and laptop machines has slowed somewhat. While companies such as Intel have continued relentlessly releasing new chips, advances have been more in the area of efficiency (and therefore battery life) than they have been raw performance. What this means is that PCs that would traditionally be nearing end of life, perhaps three to four years old, are now more viable for continued use than ever before. Of…

Resources A text editor such as Emacs or vi The Go compiler This tutorial will talk about how to perform a variety of file I/O operations in Go. After discussing the Go packages and functions needed for reading, writing and deleting files, it will show you how to deal with records, binary data and sparse files in Go. You will also learn about byte slices and how they can help you execute file I/O operations. About File I/O Figure 1 shows the Go code of naiveCP.go. The program is a naïve version of the cp command-line utility; its core functionality is based on the next two lines of Go code: Although naiveCP.go does its job, it does not implement cp in an efficient way because it reads its input file…

Once you’ve started to hone your hardware skills, then the sky (or the Pi) is the limit. From building your own toys, like remote-controlled cars or your own games machine, to media projects like a Raspberry Pi-powered picture frame or your own networked music player, to practical electronics like creating circuits and building a Bluetooth iBeacon, these are just some of the projects you can try to get started. You can find detailed guides to all of them in Raspberry Pi: The Complete Manual (http://bit.ly/2aHhSJz). Paint your own circuits Bare Conductive (www.bareconductive.com) has taken the joy of electronics and made it far safer, easier and more versatile with its conductive paint. You can literally draw wires on paper with a paintbrush; use it for cold soldering, as a conductive adhesive,…

“The Music Box is polyphonic – you can play multiple sounds at once” Playback control The three potentiometers control all the basic playback features on the music box. The red pot controls volume, green control the sound fonts used and the blue pot controls the notes that are played and the pitch they play at Using SoundFonts Mike has preloaded 32 different SoundFonts in to the music box, enabling you to create some fantastic sounds. However, by downloading your own and implementing them into the associated project folder, you’ll be able to add your own with ease if you recreate the project Playing chords One of the better things about using the GPIO Zero interface is that it’s multi-threaded. For Mike, this means he’s able to press more than one…

What you’ll need Anoldnewtoy Resistors Small disc motor LED A radio Small webcam Female-to-female jumper jerky wire Tactile button In part one of this tutorial (Linux User & Developer issue 168) you created four hacks that were originally used to augment a £3 R2D2 sweet dispenser making it light up, vibrate, play music and stream a live web feed to a mobile device. You may have been working on your own features to use and customise your toy. Part two of this tutorial begins by showing two different ways to set up and use a button to trigger your hacks. One method is to add and code your own button, the second method is to utilise the toy’s own built-in button. The next part walks you through how to…

Sometimes the simplest games are the best, and sometimes they’re far from simple. Side scrollers are easy to play when it’s just a jumping penguin, but with a space rocket and Newtonian physics, our first few attempts at Galaxy Forces V2 ended in small fireballs as the ship crashed. Fortunately we’re persistent here at LUD Towers, and our old 2D-playing reflexes eventually asserted themselves. A good thing too, for there’s a lot to get to in this game - inspired by Gravity Force on the Amiga – with 50 levels, multiple opponents, and four modes. Start with the race mode against the clock, then with up to eight players over the network. Now challenge yourself with a dogfight against the (still developing) AI. Last, missions involve transporting cargo – competitively…

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